Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Consolidated Statement of Comprehensive Income [Abstract]
Net income	$ 79,857	$ 69,835	$ 191,691	$ 202,121
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax		1,007		(448)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax			1,153
Change in cumulative translation adjustment	(14,439)	10,942	(8,720)	(2,203)
Comprehensive income	$ 65,418	$ 81,784	$ 184,124	$ 199,470